Liquid water resistant and water vapor permeable garments

ABSTRACT

A water resistant garment having regions of high MVTR while maintaining water resistance. The garment has a nanofiber layer bonded to, and in a face-to-face relationship with, a fabric layer. Optionally a second fabric layer is bonded adjacent to and in a face-to-face relationship with the nanofiber layer and on the opposite side of the nanofiber layer to the first fabric layer. The garment has regions having a Frazier air permeability of no greater than about 25 cfm/ft 2 , an MVTR per ASTM E-96B method of greater than about 500 g/m 2 /day and a hydrohead of at least about 50 cmwc.

FIELD OF THE INVENTION

This invention relates to garments with controlled moisture vapor andwater management capability. The invention as claimed and disclosed hasparticular applications in outerwear.

BACKGROUND OF THE INVENTION

Protective garments for wear in rain and other wet conditions shouldkeep the wearer dry by preventing the leakage of water into the garmentand by allowing perspiration to evaporate from the wearer to theatmosphere. “Breathable” materials that do permit evaporation ofperspiration have tended to wet through from the rain, and they are nottruly waterproof. Oilskins, polyurethane coated fabrics, polyvinylchloride films and other materials are waterproof but do not allowsatisfactory evaporation of perspiration.

Fabrics treated with silicone, fluorocarbon, and other water repellantsusually allow evaporation of perspiration but are only marginallywaterproof; they allow water to leak through under very low pressuresand usually leak spontaneously when rubbed or mechanically flexed. Raingarments must withstand the impingement pressure of falling and windblown rain and the pressures that are generated in folds and creases inthe garment.

It is widely recognized that garments must be “breathable” to becomfortable. Two factors that contribute to the level of comfort of agarment include the amount of air that does or does not pass through agarment as well as the amount of perspiration transmitted from inside tooutside so that the undergarments do not become wet and so naturalevaporative cooling effects can be achieved. However even recentdevelopments in breathable fabric articles using microporous films tendto limit moisture vapor transmission if air permeability is to becontrolled.

Many waterproof structures currently available comprise a multilayerfabric structure that employs the use of a hydrophobic coating. Thisfabric structure is typically made of a woven fabric layer, ananoweb-type microporous layer, and another woven or knit layer. Themicroporous layer is the functional layer of the construction thatprovides the appropriate air permeability and moisture vaportransmission rate necessary for the targeted application. For examplesof such structures see U.S. Pat. Nos. 5,217,782; 4,535,008; 4,560,611and 5,204,156.

If a hydrophobic coating is to be applied to the fabric structure, thenthe technology currently available in the market is overdesigned for theapplication. A fabric is needed that provides an acceptable level ofliquid water resistance and high moisture vapor transmission at a lowercost and higher productivity.

It is known that for a garment to be comfortable, it must accommodatethe body's physiological need for thermal regulation. In warmenvironments, heat energy must be expelled from the body. This is doneprincipally by a combination of direct thermal conduction of heat awayfrom the body through the fabric and air layers at the skin surface,convection of heat away from the body by flowing air, and by the coolingeffects of evaporation of sweat from the surface of the skin. Clothingwhich appreciably inhibits heat transfer can cause heat and moisturebuildup and this can result in discomfort due to warm, sticky, clammyand or sweaty sensations. In the extreme case, for example, whereprotective clothing prevents adequate thermal regulation during activityin a warm and humid environment, such clothing limitations not only leadto discomfort, but can result in life-threatening heat stress. For thisreason, frequently, clothing limitations impose limitations on activityto avoid the consequences of heat stress.

Studies have shown that the most comfortable garments with the leastrestrictions on physical activity in warm, humid environments are thosemost able to breathe through mechanisms of air exchange with theenvironment. (Bernard, T. E., N. W. Gonzales, N. L. Carroll, M. A.Bryner and J. P. Zeigler. “Sustained work rate for five clothingensembles and the relationship to air permeability and moisture vaportransmission rate.” American Industrial Hygiene Conference, Toronto,June 1999; N. W. Gonzales, “Maximum Sustainable Work for Five ProtectiveClothing Ensembles and the Effects of Moisture Vapor Transmission Ratesand Air Permeability” Master's Thesis, College of Public Health,University of South Florida, December 1998).

Physical activity flexes fabric and garment. If a fabric has low enoughresistance to air flow, this flexure produces a pumping action whichpushes and pulls air back and forth through the fabric. By thismechanism, the exchange of warm moisture laden air within the garmentwith ambient air provides a significant cooling effect. Tests ofprotective garments made of the same cut, but with widely differing airflow resistance under warm humid conditions (32° C., 60% RH), have shownthat the garments made of fabrics with the least air flow resistancerepeatedly allowed subjects to achieve higher levels of activity withoutincurring heat stress. Conversely, garments made of fabrics with thehighest air flow resistance limited the physical activity of the samesubjects to the lowest levels to avoid heat stress. Garments made offabrics having intermediate air flow resistance allowed subjects toachieve intermediate levels of activity without heat stress. Theintermediate activity levels correlated very well with the air flowresistance of the fabric.

Clearly, under conditions where the body must transfer heat and moistureto maintain comfort or avoid heat stress, it is desirable for garmentsto be made with fabrics having low air flow resistance.

Clothing provides protection from hazards in the environment. The degreeof protection clothing imparts is dependent upon the effectiveness ofthe barrier characteristics of the clothing. Where the function of thebarrier is to keep environmental particulates or fluids from penetratinga garment to reach the wearer, barrier is easily correlated with fabricpore size. The most effective barriers generally have the smallest poresize.

Unfortunately, smaller pore size also generally results in higher airflow resistance. In the studies cited above, the garments with thehighest barrier properties had the lowest air flow permeability and viceversa. So the ability to provide effective barrier protection inclothing and the ability to provide low air flow resistance, i.e., highair flow permeability, in the same garment are inversely related.

Microporous films have been used in barrier materials to achieveextremely high hydrostatic head liquid barrier properties, but at theexpense of breathability, such that their air permeabilities areunacceptably low, rendering fabrics containing such films uncomfortablefor the wearer.

The present invention is directed towards a layered material for agarment that provides controlled liquid water resistance in the presenceof high vapor transmittance.

SUMMARY OF THE INVENTION

In a first embodiment, the present invention is directed to awaterproof, breathable garment having the ability to pass moisture vaporwhile protecting the wearer from water comprising a composite fabric ofa first outer fabric layer adjacent to and in a face-to-facerelationship with a nanofiber layer, wherein the nanofiber layercomprises at least one porous layer of polymeric nanofibers having anumber average diameter between about 50 nm to about 1000 nm, a basisweight of between about 1 g/m² and about 100 g/m², and the compositefabric has a Frazier air permeability of between about 1.2 m³/m²/min andabout 7.6 m³/m²/min, an MVTR of greater than about 500 g/m²/day, and ahydrostatic head of at least about 50 cm of water.

DETAILED DESCRIPTION

The terms “nanofiber layer” and “nanoweb” are used interchangeablyherein and refer to a nonwoven web of nanofibers.

The term “nanofiber” as used herein refers to fibers having a numberaverage diameter or cross-section less than about 1000 nm, even lessthan about 800 nm, even between about 50 nm and 500 nm, and even betweenabout 100 and 400 nm. The term diameter as used herein includes thegreatest cross-section of non-round shapes.

The term “nonwoven” means a web including a multitude of randomlydistributed fibers. The fibers generally can be bonded to each other orcan be unbonded. The fibers can be staple fibers or continuous fibers.The fibers can comprise a single material or a multitude of materials,either as a combination of different fibers or as a combination ofsimilar fibers each comprised of different materials.

“Meltblown fibers” are fibers formed by extruding a molten thermoplasticmaterial through a plurality of fine, usually circular, die capillariesas molten threads or filaments into converging, usually hot and highvelocity, gas, e.g. air, streams to attenuate the filaments of moltenthermoplastic material and form fibers. During the meltblowing process,the diameter of the molten filaments is reduced by the drawing air to adesired size. Thereafter, the meltblown fibers are carried by the highvelocity gas stream and are deposited on a collecting surface to form aweb of randomly disbursed meltblown fibers. Such a process is disclosed,for example, in U.S. Pat. No. 3,849,241 to Buntin et al., U.S. Pat. No.4,526,733 to Lau, and U.S. Pat. No. 5,160,746 to Dodge, II et al., allof which are hereby incorporated herein by this reference. Meltblownfibers may be continuous or discontinuous.

“Calendering” is the process of passing a web through a nip between tworolls. The rolls may be in contact with each other, or there may be afixed or variable gap between the roll surfaces. Advantageously the nipis formed between a soft roll and a hard roll. The “soft roll” is a rollthat deforms under the pressure applied to keep two rolls in a calendertogether. The “hard roll” is a roll with a surface in which nodeformation that has a significant effect on the process or productoccurs under the pressure of the process. An “unpatterned” roll is onewhich has a smooth surface within the capability of the process used tomanufacture them. There are no points or patterns to deliberatelyproduce a pattern on the web as it passed through the nip, unlike apoint bonding roll.

By “garment” is meant any item that is worn by the user to protect someregion of the user's body from weather or other factors in theenvironment outside the body. For example coats, jackets, hats, gloves,shoes, socks, and shirts would all be considered garments under thisdefinition.

In one embodiment, the invention is directed to a waterproof garmenthaving the ability to maintain a high MVTR while controlling liquidwater penetration. The garment comprises a nanofiber layer that in turncomprises at least one porous layer of polymeric nanofibers having abasis weight of between about 1 g/m² and about 100 g/m².

The invention further comprises a garment comprising a composite of afirst fabric layer adjacent to and in a face-to-face relationship withthe nanofiber layer, and optionally a second fabric layer adjacent toand in a face-to-face relationship with the nanofiber layer and on theopposite side of the nanofiber layer to the first fabric layer.

The garment of the invention further has a Frazier air permeability ofno greater than about 7.6 m³/m²/min, and an MVTR per ASTM E-96B methodof greater than about 500 g/m²/day, and a hydrostatic head of at leastabout 50 centimeters of water column (cmwc).

The nonwoven web may comprise primarily or exclusively nanofibers thatare produced by electrospinning, such as classical electrospinning orelectroblowing, and in certain circumstances by meltblowing processes.Classical electrospinning is a technique illustrated in U.S. Pat. No.4,127,706, incorporated herein in its entirety, wherein a high voltageis applied to a polymer in solution to create nanofibers and nonwovenmats. The nonwoven web may also comprise melt blown fibers.

The “electroblowing” process for producing nanowebs is disclosed inWorld Patent Publication No. WO 03/080905, incorporated herein byreference in its entirety. A stream of polymeric solution comprising apolymer and a solvent is fed from a storage tank to a series of spinningnozzles within a spinneret, to which a high voltage is applied andthrough which the polymeric solution is discharged. Meanwhile,compressed air that is optionally heated is issued from air nozzlesdisposed in the sides of or at the periphery of the spinning nozzle. Theair is directed generally downward as a blowing gas stream whichenvelopes and forwards the newly issued polymeric solution and aids inthe formation of the fibrous web, which is collected on a groundedporous collection belt above a vacuum chamber. The electroblowingprocess permits formation of commercial sizes and quantities of nanowebsat basis weights in excess of about 1 gsm, even as high as about 40 gsmor greater, in a relatively short time period.

The fabric layer of the invention can be arranged on the collector tocollect and combine the nanoweb spun on the fabric, so that thecomposite is used as the fabric of the invention.

Polymer materials that can be used in forming the nanowebs of theinvention are not particularly limited and include both addition polymerand condensation polymer materials such as, polyacetal, polyamide,polyester, polyolefins, cellulose ether and ester, polyalkylene sulfide,polyarylene oxide, polysulfone, modified polysulfone polymers andmixtures thereof. Preferred materials that fall within these genericclasses include, poly(vinylchloride), polymethylmethacrylate (and otheracrylic resins), polystyrene, and copolymers thereof (including ABA typeblock copolymers), poly(vinylidene fluoride), poly(vinylidene chloride),polyvinylalcohol in various degrees of hydrolysis (87% to 99.5%) incrosslinked and non-crosslinked forms. Preferred addition polymers tendto be glassy (a T_(g) greater than room temperature). This is the casefor polyvinylchloride and polymethylmethacrylate, polystyrene polymercompositions or alloys or low in crystallinity for polyvinylidenefluoride and polyvinylalcohol materials. One preferred class ofpolyamide condensation polymers are nylon materials, such as nylon-6,nylon-6,6, nylon 6,6-6,10 and the like. When the polymer nanowebs of theinvention are formed by meltblowing, any thermoplastic polymer capableof being meltblown into nanofibers can be used, including, polyesterssuch as poly(ethylene terephthalate) and polyamides, such as the nylonpolymers listed above.

The as-spun nanoweb of the present invention can be calendered in orderto impart the desired physical properties to the fabric of theinvention. In one embodiment of the invention the as-spun nanoweb is fedinto the nip between two unpatterned rolls in which one roll is anunpatterned soft roll and one roll is an unpatterned hard roll, and thetemperature of the hard roll is maintained at a temperature that isbetween the T_(g), herein defined as the temperature at which thepolymer undergoes a transition from glassy to rubbery state, and theT_(om), herein defined as the temperature of the onset of melting of thepolymer, such that the nanofibers of the nanoweb are at a plasticizedstate when passing through the calendar nip. The composition andhardness of the rolls can be varied to yield the desired end useproperties of the fabric. In one embodiment of the invention, one rollis a hard metal, such as stainless steel, and the other a soft-metal orpolymer-coated roll or a composite roll having a hardness less thanRockwell B 70. The residence time of the web in the nip between the tworolls is controlled by the line speed of the web, preferably betweenabout 1 m/min and about 50 m/min, and the footprint between the tworolls is the MD distance that the web travels in contact with both rollssimultaneously. The footprint is controlled by the pressure exerted atthe nip between the two rolls and is measured generally in force perlinear CD dimension of roll, and is preferably between about 1 mm andabout 30 mm.

Further, the nanoweb can be stretched, optionally while being heated toa temperature that is between the T_(g) and the lowest T_(om) of thenanofiber polymer. The stretching can take place either before and/orafter the web is fed to the calender rolls and in either or both themachine direction or cross direction.

A hydrophobic nonwoven sheet containing nanofibers can be producedaccording to the present invention by depositing a nanoweb ofconventional hydrophilic polymer nanofibers onto a collecting/supportingweb and treating the web's nanofibers with a hydrophobic treatment, suchas a fluorocarbon material. When the coating material is applied in anextremely thin layer, little if any change in the air permeabilityproperties of the underlying web is caused, for example as described inco-pending U.S. provisional application No. 60/391,864, filed 26 Jun.2002. Alternatively, the formed nanoweb can be immersed in a solution ofa coating material, for example a fluorosurfactant, and then dried.

In a preferred embodiment of the invention the fluorinated surfactant isone of the Zonyl® line of surfactants produced by the DuPont company.

A wide variety of natural and synthetic fabrics are known and may beused as the fabric layer or layers in the present invention, forexample, for constructing garments, such as sportswear, rugged outerwearand outdoor gear, protective clothing, etc. (for example, gloves,aprons, chaps, pants, boots, gators, shirts, jackets, coats, socks,shoes, undergarments, vests, waders, hats, gauntlets, sleeping bags,tents, etc.). Typically, vestments designed for use as rugged outerwearhave been constructed of relatively loosely-woven fabrics made fromnatural and/or synthetic fibers having a relatively low strength ortenacity (for example, nylon, cotton, wool, silk, polyester,polyacrylic, polyolefin, etc.). Each fiber can have a tensile strengthor tenacity of less than about 8 g/Denier (gpd), more typically lessthan about 5 gpd, and in some cases below about 3 gpd. Such materialscan have a variety of beneficial properties, for example, dyeability,breathability, lightness, comfort, and in some instances,abrasion-resistance.

Different weaving structures and different weaving densities may be usedto provide several alternative woven composite fabrics as a component ofthe invention. Weaving structures such as plain woven structures,reinforced plain woven structures (with double or multiple warps and/orwefts), twill woven structures, reinforced twill woven structures (withdouble or multiple warps and/or wefts), satin woven structures,reinforced satin woven structures (with double or multiple warps and/orwefts), knits, felts, fleeces and needlepunched structures may be used.Stretch woven structures, ripstops, dobby weaves, and jacquard weavesare also suitable for use in the present invention.

The nanoweb is bonded to the fabric layers over some fraction of itssurface and can be bonded to the fabric layer by any means known to oneskilled in the art, for example adhesively, thermally, using anultrasonic field or by solvent bonding. In one embodiment the nanoweb isbonded adhesively using a solution of a polymeric adhesive such as apolyurethane and allowing the solvent to evaporate. In a furtherembodiment, when the nanoweb is electrospun directly onto a fabric layerand residual electrospinning solvent is used to achieve solvent bonding.

EXAMPLES

Hydrostatic head or “hydrohead” (ISO 811) is a convenient measure of theability of a fabric to prevent water penetration. It is presented as thepressure, in centimeters of water column (cmwc), required to forceliquid water through a fabric. It is known that hydrohead dependsinversely on pore size. Lower pore size produces higher hydrohead andhigher pore size produces lower hydrohead. A ramp rate of 60 cmwc perminute was used in the measurements below.

Fabric air flow permeability is commonly measured using the Fraziermeasurement (ASTM D737). In this measurement, a pressure difference of124.5 N/m² (0.5 inches of water column) is applied to a suitably clampedfabric sample and the resultant air flow rate is measured as Frazierpermeability or more simply as “Frazier”. Herein, Frazier permeabilityis reported in units of m³/m²/min. High Frazier corresponds to high airflow permeability and low Frazier corresponds to low air flowpermeability.

Another important parameter in apparel is the ability of the fabric toexpel moisture vapor from the inside of the jacket. This parameter iscalled the Moisture Vapor Transmission Rate (MVTR). Nanowebs were testedfor MVTR using the ASTM E96 B method and are reported in units ofg/m²/day.

Where samples are calendered, the calendaring took place at a pressureof 1.5 pounds per linear inch (pli) and 125° C.

Unless otherwise specified, fluorosurfactant treatment was by means of adip and squeeze method using hexanol at 0.6% as a wetting agent, in a400 g water bath where both sides of the nanoweb are fully submerged inthe bath. The nanoweb was then dried in an oven at 139° C. for threeminutes.

Example 1

A two-layer fabric construction made from a 170 gsm stretch nylonplain-weave fabric (available from Rose City Textiles in Portland,Oreg.) and a nanoweb made from Nylon 6,6, with a basis weight of 10 gsm(grams per square meter) was produced. The two-layer fabric constructionwas produced by laminating the nylon woven fabric to the nanoweb using asolvent-based urethane adhesive using a “288-pattern” gravure-rollapplication with a pressure of 60 psi. The final two-layer fabricconstruction was then treated with a telomeric fluorinated surfactant(Zonyl® 7040, Du Pont, Wilmington, Del.) at 8% solids (as received) in awater bath. The Zonyl® (commercially available from E. I. du Pont deNemours and Company) was applied using a dip and squeeze method whereboth sides of the construction are fully submerged in the bath. Thetwo-layer construction was then passed through an electrically heatedoven at a temperature of 140° C. with a residence time of 2 minutes and45 seconds.

The two-layer fabric construction had a hydrohead of 190 cmwc and anMVTR of 1397 g/m²/day.

Comparative Example 1

A single layer of plain-woven stretch nylon was treated with Zonyl® 7040in the same manner as described above and tested for hydrohead. Thesingle layer of woven nylon, without the nonwoven nanoweb, had ahydrohead of only 33 cmwc and an MVTR of 1916 g/m²/day.

As can be seen from Example 1 and Comparative Example 1, the nanoweb cangreatly increase the hydrohead of the fabric construction, when used incombination with a durable water repellant coating. Additionally, thehydrohead can be further increased, if desired, through post-processingof the hybrid nanoweb structure.

Example 2

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was calendared_and then treated with Zonyl® 7040 at 8% solids(as received). This treated nanoweb was then tested for hydrohead. Thefirst trial did not use any type of support system for the nanoweb, andthe resulting hydrohead was 48 cmwc. For the second trial, a coarse,mesh support screen, with two gaskets on either side at the edge, wasplaced over the nanoweb in the test clamp. This screen was used to keepthe nanoweb from bulging while applying the hydrostatic pressure. Theresulting hydrohead was 166 cmwc using this coarse mesh support screen.For the third and fourth trials, a much finer mesh support screen wasused to control the bulging of the nanoweb during the test. Theresulting hydroheads were 244 cmwc and 269 cmwc, respectively, usingthis fine mesh support screen.

Example 3

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was treated with Zonyl® 7040 at 8% solids (as received). Thefirst trial did not use any type of support system for the nanoweb, andthe resulting hydrohead was 40 cmwc. For the second, third, and fourthtrials, the fine mesh support screen was placed on top of the nanoweb inthe test clamp to stop the nanoweb from bulging during the test. Theresulting hydroheads were 202 cmwc, 214 cmwc, and 202 cmwc. MVTR was1730 g/m²/day.

Example 4

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was calendared and then treated with Zonyl® 7040 at 16%solids (as received). The first trial did not use any type of supportsystem for the nanoweb, and the resulting hydrohead was 46.5 cmwc. Forthe second and third trials, the fine mesh support screen was placed ontop of the nanoweb in the test clamp to stop the nanoweb from bulging.The resulting hydroheads were 292 cmwc and 326 cmwc, respectively. Forthe fourth trial, a 170 gsm stretch nylon plain-weave fabric (availablefrom Rose City Textiles in Portland, Oreg.) was placed on top of thenanoweb in the test clamp to stop the nanoweb from bulging. Theresulting hydrohead was 173 cmwc. For the fifth trial, two pieces of thecalendered nanoweb were layered on top of each other and then coveredwith the fine mesh support screen in the test clamp. The resultinghydrohead was 550 cmwc. MVTR was 1586 g/m²/day.

Example 5

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was treated with Zonyl® 7040 at 16% solids (as received).Both the first and second trial used the fine mesh support screen tostop the nanoweb from bulging in the test clamp. The resultinghydroheads were 266 cmwc and 282 cmwc, respectively. For the thirdtrial, the nanoweb was treated a second time by running the nanoweb backthrough the dip and squeeze method and then dried a second time in anoven at 139° C. for three minutes. The twice-treated nanoweb was thentested for hydrohead using the FX3000 Hydrostatic Tester. A fine meshsupport screen was used in the test clamp to stop the nanoweb frombulging during the test. The resulting hydrohead was 290 cmwc. MVTR was1708 g/m²/day.

Example 6

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was calendered and then treated with Zonyl® 7040 at 16%solids (as received). For all three trials, the fine mesh support screenwas used in the test clamp to stop the nanoweb from bulging during thetest. The resultant hydroheads were 490 centimeters of water column(cmwc), 454 cmwc, and 586 cmwc. MVTR was 1701 g/m²/day.

Example 7

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was calendered and then treated with Zonyl® 7040 at 28%solids (as received), using hexanol at 0.6% as a wetting agent, in a 200g water bath. In the first, second, and third trials, a fine meshsupport screen was used over the nanoweb in the test clamp to stop thenanoweb from bulging during the test. The resulting hydroheads were 372cmwc, 300 cmwc, and 318 cmwc, respectively. In the fourth and fifthtrials, two pieces of the treated nanoweb were layered on top of eachother in the test clamp and then covered with the fine mesh supportscreen. The resulting hydroheads were 360 cmwc and 509 cmwc,respectively. Average MVTR was 1660 g/m²/day.

Example 8

A single layer of the nanoweb made from Nylon 6,6, with a basis weightof 25 gsm, was calendered_and then treated with Zonyl® 7040 at 28%solids (as received), using hexanol at 0.6% as a wetting agent, in a 200g water bath. For the first trial, the fine mesh support screen was usedin the test clamp to control the bulging of the nanoweb during testing.The resultant hydrohead was 600 cmwc. For the second trial, two piecesof the nanoweb were laid on top of each other and tested using the finemesh support screen. The resultant hydrohead was 750 cmwc.

The MVTR data for the above samples are far above the industry standardand demonstrates that a durable water repellant treatment can be appliedto the nonwoven nanoweb without decreasing the MVTR to an unacceptablelevel.

1. A waterproof, breathable garment having the ability to pass moisturevapor while protecting the wearer from water comprising a compositefabric of a first outer fabric layer adjacent to and in a face-to-facerelationship with a nanofiber layer, wherein the nanofiber layercomprises at least one porous layer of polymeric nanofibers having anumber average diameter between about 50 nm to about 1000 nm, a basisweight of between about 1 g/m² and about 100 g/m², and the compositefabric has a Frazier air permeability of between about 1.2 m³/m²/min andabout 7.6 m³/m²/min, an MVTR of greater than about 500 g/m²/day, and ahydrostatic head of at least about 50 cm of water.
 2. The garment ofclaim 1 wherein the nanofiber layer and the first fabric layer arebonded to each other over a fraction of their surfaces.
 3. The garmentof claim 2 wherein a solvent-based adhesive is used to bond the layers.4. The garment of claim 2 wherein the nanofiber layer is electrospundirectly onto the surface of the first fabric layer and residual solventfrom the electrospinning process is used to bond the layers.
 5. Thegarment of claim 1 wherein the nanofiber layer comprises nanofibers of apolymer selected from the group consisting of polyacetals, polyamides,polyesters, cellulose ethers, cellulose esters, polyalkylene sulfides,polyarylene oxides, polysulfones, modified polysulfone polymers andcombinations thereof.
 6. The garment of claim 1 wherein the nanofiberlayer comprises nanofibers of a polymer selected from the groupconsisting of poly(vinylchloride), polymethylmethacrylate, polystyrene,and copolymers thereof, poly(vinylidene fluoride), poly(vinylidenechloride), polyvinylalcohol in crosslinked and non-crosslinked forms. 7.The garment of claim 5 wherein the polymer is selected from the groupconsisting of nylon-6, nylon-6,6, and nylon 6,6-6,10.
 8. The garment ofclaim 1 wherein the nanofiber layer is calendered.
 9. The garment ofclaim 8 wherein the nanofiber layer is calendered while in contact withthe first fabric layer.
 10. The garment of claim 1 wherein the nanofiberlayer is treated with a fluorinated surfactant.
 11. The garment of claim1 wherein the first fabric layer is woven from a material selected fromthe group consisting of nylon, cotton, wool, silk, polyester,polyacrylic, polyolefin, and combinations.
 12. The garment of claim 1wherein the first fabric layer is woven from fibers that have a tenacityof less than about 8 g/Denier (gpd)).